In Red do you see the duration as matching the clip duration?
If it does try trashing the FCP Cache files:
To do so go to the “GO” menu in finder and choose home. Then navigate to
Library> Preferences> Final Cut Pro User Data. Trash the “Final Cut Pro OBJ
Cache” and “Final Cut Pro Prof Cache” Launch Final Cut Pro and try again.
If it is still giving you the problem trash the Red preference files you find in the User> Library> Preferences directory.
If you are STILL seeing an issue save out the FCP project file and send it to me to look at.
mattm@borisfx.com